1. Technical Field
The present invention relates to a clamping apparatus with datum function and more particularly to an apparatus for precisely aligning a work pallet or the like movable member with a table of a machining center or the like reference member and fixing the former to the latter.
2. Description of the Earlier Technology There is a conventional technique recited in Japanese Patent Public Disclosure No. 11-10468 as an example of the clamping apparatus of this type. The conventional technique is constructed as follows.
A retracting nipple fixed to a movable member has a flange fitted into a fitting straight hole formed in a support surface of a reference member, thereby making an axis of the straight hole coincident with that of the retracting nipple. Thereafter, the retracting nipple is pulled to fix the movable member to the reference member.
However, the conventional technique has the following problem.
In order to smoothly attach the movable member to the reference member, a diametrical fitting gap is required between the fitting straight hole and the flange. The existence of that fitting gap reduces the preciseness of alignment between the both members.
The present invention aims at making it possible to smoothly attach the movable member to the reference member and to precisely align the both members with each other.
In order to accomplish the above aim, an invention of claim 1 has constructed a clamping apparatus with datum function in the following manner, for example, as shown in FIGS. 1 to 4 or in FIG. 5.
The clamping apparatus with datum function aligns a movable member (M) with a reference member (R) and fixes a surface (T) to be supported of the movable member (M) to a support surface (S) of the reference member (R). The surface (T) to be supported of the movable member (M) is opened to provide a socket bore 11, in which a positioning hole 12 and an engaging hole 13 are formed in order from an opened end. An annular plug portion 21 to be inserted into the socket bore 11 projects from the reference member (R). Arranged between the plug portion 21 and the positioning hole 12 is a shuttle member 23 which expands and contracts diametrically. The shuttle member 23 is supported by one 21(12) of the plug portion 21 and the positioning hole 12 so as to be axially movable within a predetermined range. It can also make a tapering engagement with the other 12(21). The shuttle member 23 has a tapered surface 28 formed so as to narrow toward the engaging hole 13. A resilient member 24 urges the shuttle member 23 in a direction for tightening the tapering engagement. A pull rod 31 is inserted axially movably into a cylindrical hole 21a of the plug portion 21. The pull rod 31 has an outer peripheral space in which there is arranged an engaging member 34 movable between a radially outward engaging position (X) and a radially inward disengaging position (Y). A driving means (D) provided in the reference member (R) drives the pull rod 31 for clamping in a direction toward a base end (a first end), thereby enabling an output portion 36 of the pull rod 31 to switch over the engaging member 34 to the engaging position (X) for engaging it with the engaging hole 13 to move the movable member (M) toward the reference member (R). The driving means (D) drives the pull rod 31 for unclamping in a direction toward a leading end (a second end), thereby allowing the engaging member 34 to switch over to the disengaging position (Y).
The invention of claim 1 produces the following function and effect.
When clamping a movable member to a reference member, first, the movable member automatically moves while aligning by a guide action of a tapered surface of a shuttle member to make an axis of a positioning hole of the movable member precisely coincident with that of a plug portion of the reference member. Next, the shuttle member compresses a resilient member and axially moves, thereby enabling a support surface of the reference member to receive a surface to be supported of the movable member. Thus the movable member is constrained through the tapered surface of the shuttle member by the plug portion as well as by the support surface. As a result, the movable member can be precisely and strongly positioned and fixed to the reference member.
According to the present invention, the tapered surface of the shuttle member can guide the movable member while it is aligning, which results in the possibility of smoothly attaching the movable member to the reference member. Further, differently from the conventional technique, the present invention can get rid of a diametrical fitting gap between members to be connected to one another and therefore can align the movable member with the reference member with a high accuracy.
In addition, the plug portion is disposed in the reference member provided with a driving means. When compared with a case where the reference member is provided with a socket bore, the present invention can prevent chips or the like foreign matters from invading the driving means. Therefore, it is possible to use the clamping apparatus in a good condition over a long period of time.
The present invention is preferably constructed as indicated by an invention of claim 2.
For example, as shown in FIGS. 2 to 4, the shuttle member 23 has an inner peripheral surface formed by a straight surface 27 and an outer peripheral surface constructed by a tapered surface 28. The straight surface 27 is supported by the plug portion 21 so as to be axially movable and the tapered surface 28 makes a tapering engagement with the positioning hole 12.
The invention of claim 2 has equipped the shuttle member in the reference member. Accordingly, in the case where a large number of movable members are attached to and detached from one reference member, it is sufficient even if the shuttle member is equipped in a small number. This can construct a clamping system simply.
As indicated by an invention of claim 3, the invention as set forth in claim 1 or 2 is preferably constructed in the following manner.
For example, as shown in FIG. 3, when the pull rod 31 is driven for unclamping, a leading end of the pull rod 31 pushes a top wall 11a of the socket bore 11, thereby forming a fitting gap (xcex1) on the tapered surface 28 of the shuttle member 23 and a contact gap (xcex2) between the support surface (S) and the surface (T) to be supported.
The invention of claim 3 produces an effect of being able to easily remove the movable member from the reference member owing to the existence of the above-mentioned fitting gap and contact gap.
As indicated by an invention of claim 4, the invention as set forth in any one of claims 1 to 3 is preferably constructed in the following manner.
The reference member (R) is provided with a supply port 41 for cleaning fluid and the leading end of the pull rod 31 is provided with a blowout hole 42 for the cleaning fluid. The supply port 41 communicates with the blowout hole 42 through a flow passage 44 within the pull rod 31.
The invention of claim 4 produces an effect of being able to prevent misengagement between the reference member and the movable member because the cleaning fluid discharged through the blowout hole can clean the fitting gap and the contact gap between the both members.